9 White Lies You Need to Stop Telling Your Docs

If you're not telling the whole truth (and nothing but the truth), you could be harming your health

The lie: "I've only been sleeping with my S.O. Singular." Also heard: "We always use a condom."

Why you should 'fess up: Keeping your sexual history under lock and key prevents your doctor from keeping a watchful eye for STDs that can hurt you down the line ... and from prescribing you meds that could potentially harm a fetus. Don't be embarrassed -- doctors have literally seen and heard it all. "I have had teenagers tell me they've never had sex only to get back a positive pregnancy test or a positive STD test," says Dr. Bola Oyeyipo, a family physician in San Antonio, TX.

OK so, that STD you got -- and treated -- way back when, or that night of unprotected sex with some dude whose name you never caught: You can pretend like it never happened, right? Wrong. Even if your initial tests came back clean, it can take up to six months for HIV to show up, says Agarwal. If you're at risk, your doctor will insist on a follow-up test. Plus, gonorrhea or chlamydia increase your risk for ectopic pregnancies -- your doctor needs to know this history to keep a close eye on you if you do get pregnant.

Oh, and this goes double for spilling the beans about your partners' sexual history. Don't hold back if your partner cheated, or you slept with someone who sleeps around (which is safe to assume if it's a one-night-stand).